Retainer for rotatable cutting bit

ABSTRACT

A retainer for mounting and retaining a rotatable cutting tool or bit in a block bore. The cutting tool contains an annular channel. The retainer has an unstressed diameter greater than the diameter of the bore so that when the cutting tool is inserted into the bore, the retainer expands against the bore so as to be held therein along with the cutting tool. The retainer comprises a cylindrical sleeve having an engaging member extending circumferentially around the sleeve and having a constant cross section shape which projects into the annular channel of the cutting tool and which annular channel has an inward rectangular surface corresponding to the inward engaging member of the retainer for receiving and retaining the retainer to the cutting tool.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/317,719 filed Mar. 26, 2010, which is fully incorporated herein by reference.

FIELD OF THE INVENTION

The invention pertains to an earth working, mining, or construction bit, and more particularly, to a retainer wear sleeve for holding a rotatable cutting bit in a mounting block that is affixed to a movable member.

BACKGROUND

Rotatable cutting bits held within a mounting block affixed to a movable member, such as a mining wheel or road planning drum, are utilized to perform various excavating operations, which include applications relating to the removal of minerals as well as applications relating to road planning, trenching, concrete cutting and other construction applications.

Prior art cutting bits have utilized an enlarged diameter or sharply stepped rearward portion of the bit as an abutment to retain a cylindrical retainer or clip captive on the bit. In operation of the prior art bits and retainers, the rearward portion of the bit contacts the cylindrical wall of the bore so that wear on certain portions of the bore occurs as the bit rotates in the mounting block. U.S. Pat. No. 4,850,649 to Wayne H. Beach, et al. provides a retainer wear sleeve which protects the bore of the block from wear due to contact with the shank of the cutting bit during operation. Such a retainer wear sleeve increases the life of the block since contact between the shank and the bore of the block is reduced.

During the cutting operation, a large volume of particulate materials are generated. These particulates tend to infiltrate the bore of the block-bit assembly, and collect in the volume between the rear shank and the retainer wear sleeve. The prior art cutting bits having an enlarged diameter or sharply stepped rearward portion have trapped these contaminates, and impaired the ability of the bit either to rotate in the bore of or to be efficiently removed from the block. The retainer wear sleeve of the above mentioned U.S. Pat. No. 4,850,649 to Wayne H. Beach, et al. reduces the tendency of particulate material being trapped between the sleeve and the shank. This '649 patent discloses a retainer wear sleeve either having projecting dimples, an annular projection or equi-spaced circumferential projections which are received within an annular channel of the cutting bit for retaining the sleeve to the shank of the bit.

There is a need to provide a retainer for a rotatable cutting bit which is sturdier than known retainer wear sleeves.

There is a further need to provide a retainer for a rotatable cutting bit that comprises an engaging member projecting into an annular channel of the cutting bit and which engaging member has a cross-sectional area that is greater than the engaging devices of known retainer wear sleeves.

SUMMARY

An aspect of the present invention is to provide a retainer for a rotatable cutting bit for mounting and retaining the rotatable cutting bit in a bore of a block that is affixed to a movable member. In one aspect, the invention comprises a retainer and a cutting tool or bit for mounting in the bore of the block wherein the cutting tool comprises an elongated bit body generally symmetrical about a longitudinal axis. The elongated body has forward and rearward portions wherein the forward portion terminates in a front end at which there is a cutting tip and the rearward portion is of a generally constant diameter and terminates in a rear end. The rearward portion contains an annular channel or groove adjacent the rear end thereof. A resilient retainer comprising a wear sleeve surrounds substantially the peripheral rearward shank portion and extends rearwardly past the rear end and has an inward engaging member received within the annular channel so that the elongated body and retainer are retained together. The retainer has an unstressed diameter greater than the diameter of the bore so that when the cutting tool is inserted into the bore, the retainer expands against the bore so as to be held therein. In one aspect, the retainer comprises an inward engaging member comprising a constant cross-sectional shape. In another aspect, the inward engaging member has a generally symmetrical shape about a central longitudinal axis thereof. In another aspect, the inward engaging member may have a generally rectangular cross-sectional shape. The annular channel of the cutting bit has an inward surface which corresponds in shape to the inward engaging member, e.g. generally rectangular, of the retainer so that the inward engaging member is received in the annular channel when the retainer is mounted around the shank of the cutting bit, resulting in the retainer and cutting bit being retained together.

These and various other features and advantages will be apparent from the following drawings and detailed description.

DRAWINGS

FIG. 1 is a side view of a cutting bit-block assembly wherein the cutting bit is inserted into the block and the block is affixed to a movable member.

FIG. 2 is the cutting body of FIG. 1 and a retainer of the invention.

FIG. 3 is the retainer of the invention mounted onto the shank of a cutting tool.

FIG. 4 is a cross-sectional view of the retainer of FIG. 2.

FIG. 5 is an end view of the retainer of FIG. 4.

FIG. 6 is a sketch of a cutting body and a retainer of the invention similar to that of FIG. 2.

FIG. 7 is a perspective view of the cylindrical sleeve of the retainer of FIG. 6.

FIG. 8 is an open flat cross sectional view of the cylindrical sleeve of FIG. 7.

DETAILED DESCRIPTION

Referring to the drawings, there is illustrated in FIG. 1 a cutting assembly generally designated as 10 which is mounted to a rotatable or movable member 12. Although not intended to be limiting, the rotatable or movable member may comprise a mining wheel, a road planning drum, a bucket blade, a grader blade or the like. The cutting assembly 10 includes a block 14 having a front face 16, a rear face 18, and a mounting face 20. As disclosed in the above discussed U.S. Pat. No. 4,850,649, which is incorporated herein by reference, block 14 includes a generally cylindrical bore having a frusto-conically shaped seating surface adjacent the front face 16 thereof. As can be appreciated from FIG. 1, the block 14 is affixed at the mounting face 20 to the rotatable member 12 such as by welding or the like.

Referring to FIGS. 1-3, cutting assembly 10 further includes a rotatable or movable cutting tool or bit generally designated as 30. Cutting bit 30 includes an elongated steel body 32 having integral forward and rearward portions 34 and 36, respectively. An annular frusto-conically shaped shoulder 38 joins the forward and rearward portions. Body 32 further includes an annular shoulder 40 positioned forwardly of annular shoulder 38.

Forward portion 34 includes a flat front face 42 having a socket (not shown) contained therein in which a cutting tip 44 is affixed such as by brazing. Cutting tip 44 is made from a hard material such as a cemented tungsten carbide.

The rearward portion 36 of steel body 32 terminates in a flat rear end 46 and contains an annular channel 50 positioned forwardly of the flat rear end 46. A constant diameter cylindrical portion 52 then joins the annular channel 50 with the annular shoulder 38.

As illustrated in FIGS. 2 and 3, a retainer generally designated as 54 surrounds substantially the rearward portion 36 of the cutting bit body 32. The retainer 54 serves two basic purposes. The first is to retain the bit body 32 in the block 14, and the second is to protect the block 14 from wear by functioning as a wear sleeve between the bit body 32 and the block 14.

Referring to FIGS. 4, 6, and 7, retainer 54 comprises an elongate cylindrical sleeve 56 having a forward portion 58 and a rearward portion 60. The forward portion 58 terminates in a generally circularly-shaped front edge 62 and the rearward portion 60 terminates in a generally circularly-shaped rearward edge 64.

The forward portion 58 of cylindrical sleeve 56 contains an inward engaging member 66 positioned forwardly of the juncture between the forward and rearward portions 58, 60 of sleeve 56. In one aspect, the inward engaging member 66 may have, for example, a generally rectangular cross-sectional shape as shown in the Figures. However, it will be appreciated that the inward engaging member 66 may have other shapes as well in accordance with the invention. As can be appreciated from FIGS. 2 and 3, the retainer 54 is positioned relative to the cutting bit body 32 so as to surround the rearward portion 36 thereof whereby the inward engaging member 66 is received within the annular channel 50 of cylindrical portion 52 of body bit 32. In one aspect, the annular channel 50 has an inward surface which corresponds in shape to the inward engaging member 66, e.g. generally rectangular, so that the inward engaging member 66 is received in the annular channel 50.

The diameter of the forward portion 58 and rearward portion 60 of sleeve 56 of retainer 54 in an unstressed condition is larger than the diameter of the bore of block 14. Consequently, when the assembly of the cutting bit body 32 and the retainer 54 is inserted into the bore of the block 14, the diameter of the forward portion 58 and the rearward portion 60 of the retainer 54 is radially compressed whereby when inside the bore, the retainer 54 expands against the bore so as to be securely held therein. Inward engaging member 66 of retainer 54 is received within annular channel or groove 50 so as to retain the cutting bit body 32 and retainer 54 together. The dimensioning of inward engaging member 66 relative to the annular channel or groove 50 and the cylindrical sleeve 56 itself relative to the rearward portion 36 of the cutting bit body 32 are as such that the cutting bit 30 is free to rotate relative to the retainer 54 and the block 14 when the cutting bit-retainer assembly is inserted into the bore of block 14. As can be appreciated, the cutting bit body 32 is rotatably retained by the retainer 54 which is securely held in the bore of block 14. The end result being that the bit is rotatably mounted within the block 14.

FIG. 5 shows that retainer 54 is a split ring wherein the longitudinal edges 70 and 72 of sleeve 56 of retainer 54 form an opening defined by the edges 70 and 72. As best shown in FIG. 6, retainer 54 is mounted around body bit 32 such that the inward engaging member 66 enters and is received in annular channel or groove 50. FIG. 7 illustrates that the inward engaging member 66 of the cylindrical sleeve 56 is an annular radial projection extending circumferentially around the inner surface 78 of cylindrical sleeve 56.

As particularly shown in FIGS. 4, 6 and 7, the inward engaging member 66 has a constant cross-sectional shape. In other words, the shape of the inward engaging member 66 remains the same from where it contacts the inner surface 78 of the cylindrical sleeve 56 to its inner most portion 67 that extends inwardly toward the center portion of the sleeve 56. In addition, the shape of the inward engaging member may be characterized as generally symmetrical about a longitudinal central axis CL thereof (see FIG. 7). In one aspect, the axis CL extends generally parallel to the vertical wall 57 of the sleeve 56.

As shown in FIG. 8, the cylindrical sleeve 56 comprises a T-shape configuration along the longitudinal axis of the cylindrical sleeve 56. It is to be appreciated that retainer 54 is made of a hard material, for example, steel.

As best shown in FIGS. 6, 7 and 8, the inward engaging member 66 of cylindrical sleeve 56 generally has a rectangular cross section and as shown particularly in FIG. 6, annular channel 50 of the shank of body bit 32 generally has a rectangular cross-sectional surface 68 that corresponds to the rectangular cross section of engaging member 66 of cylindrical sleeve 56 so that when retainer 56 is positioned around body bit 32, the inward engaging member 66 enters into the annular channel 50 of body bit 32. This structure for retainer 52 is advantageous in that more surface area is provided thereby resulting in a more sturdy structure for retainer 52.

The implementation described above and other implementations are within the scope of the described invention and the following claims. 

What is claimed is:
 1. A cutting tool for mounting in the bore of a block, the cutting tool, comprising: an elongated body generally symmetrical about a longitudinal axis having forward and rearward portions, the forward portion terminating in a front end at which there is a cutting tip, the rearward portion being of a generally constant diameter and terminating in a rear end; the rearward portion containing an annular channel adjacent the rear end; a resilient retainer surrounding substantially the rearward portion, the retainer comprising a cylindrical sleeve being axially split along the entire length thereof, the sleeve having opposite front and rear ends, and having an inward engaging member received within the annular channel so that the elongated body and retainer are retained together; and wherein the inward engaging member of the resilient retainer comprises a constant cross sectional shape extending circumferentially around the cylindrical sleeve.
 2. The cutting tool of claim 1, wherein the annular channel has generally the same cross sectional shape as the inward engaging member.
 3. The cutting tool of claim 1, wherein the inward engaging member has a generally rectangular cross sectional shape.
 4. The cutting tool of claim 3, wherein the annular channel of the rearward portion of the elongated body of the cutting tool has an inward rectangular surface corresponding to the generally rectangular cross sectional shape of the inward engaging member of the cylindrical sleeve.
 5. The cutting tool of claim 1, wherein the inward engaging member of the cylindrical sleeve is an annular radial projection extending around the circumferential inner surface of the cylindrical sleeve.
 6. The cutting tool of claim 1, wherein the cylindrical sleeve and the inward engaging member of the cylindrical sleeve form a T-shape configuration along the longitudinal axis of the cylindrical sleeve.
 7. The cutting tool of claim 1, wherein the retainer has an unstressed diameter greater than the diameter of the bore so that when the cutting tool is inserted into the bore the retainer expands against the bore so as to be held therein.
 8. A resilient retainer for rotatably mounting a rotatable cutting bit in the cylindrical bore of a block, comprising: an elongate cylindrical sleeve being axially split along the entire length thereof, the sleeve having opposite front and rear ends, an inward engaging member extending substantially around an inner periphery thereof, wherein the inward engaging member has a constant cross sectional shape.
 9. The retainer of claim 8, wherein the inward engaging member has a generally rectangular cross sectional shape.
 10. The retainer of claim 8, wherein the inward engaging member of the cylindrical sleeve is an annular radial projection extending around the circumferential inner surface of the cylindrical sleeve.
 11. The retainer of claim 8, wherein the cylindrical sleeve and the inward engaging member of the cylindrical sleeve form a T-shape configuration along the longitudinal axis of the cylindrical sleeve.
 12. A cutting tool for mounting in the bore of a block, the cutting tool, comprising: an elongated body generally symmetrical about a longitudinal axis having forward and rearward portions, the forward portion terminating in a front end at which there is a cutting tip, the rearward portion being of a generally constant diameter and terminating in a rear end; the rearward portion containing an annular channel adjacent the rear end; a resilient retainer surrounding substantially the rearward portion, the retainer comprising a cylindrical sleeve being axially split along the entire length thereof, the sleeve having opposite front and rear ends, and having an inward engaging member received within the annular channel so that the elongated body and retainer are retained together; and wherein the inward engaging member of the resilient retainer has a generally symmetrical shape about a central longitudinal axis thereof.
 13. The cutting tool of claim 12, wherein the annular channel has generally the same cross sectional shape as the inward engaging member.
 14. The cutting tool of claim 12, wherein the inward engaging member has a generally rectangular cross sectional shape.
 15. The cutting tool of claim 14, wherein the annular channel of the rearward portion of the elongated body of the cutting tool has an inward rectangular surface corresponding to the generally rectangular cross sectional shape of the inward engaging member of the cylindrical sleeve.
 16. The cutting tool of claim 12, wherein the central longitudinal axis of the inward engaging member extends generally parallel to a wall of the cylindrical sleeve.
 17. A resilient retainer for rotatably mounting a rotatable cutting bit in the cylindrical bore of a block, comprising: an elongate cylindrical sleeve being axially split along the entire length thereof, the sleeve having opposite front and rear ends, an inward engaging member extending substantially around an inner periphery thereof, wherein the inward engaging member has a generally symmetrical shape about a central longitudinal axis thereof.
 18. The retainer of claim 17, wherein the inward engaging member has a generally rectangular cross sectional shape.
 19. The retainer of claim 17, wherein the central longitudinal axis of the inward engaging member extends generally parallel to a longitudinal axis of the cylindrical sleeve.
 20. The retainer of claim 17, wherein the cylindrical sleeve and the inward engaging member of the cylindrical sleeve form a T-shape configuration along the longitudinal axis of the cylindrical sleeve. 